Getting a mortgage is the biggest financial commitment most people make. Yet many buyers walk into lender conversations without understanding how affordability is actually assessed — and end up confused when the offer differs from simple online estimates. This guide explains the full picture: income multiples, stress tests, LTV ratios, credit considerations, and all the costs beyond the deposit.
How Much Can You Borrow? Income Multiples
UK lenders typically lend between 4 and 4.5 times your annual gross income. For joint applications, most lenders use combined gross income. Some examples:
- Single applicant earning £40,000: likely to borrow £160,000–£180,000.
- Joint applicants earning £35,000 + £25,000 (£60,000 combined): likely to borrow £240,000–£270,000.
- High-earning professionals (doctors, solicitors, accountants): some specialist lenders offer 5–5.5× for those earning £75,000+ in stable professions.
Use our Mortgage Calculator to model monthly repayments at different loan amounts and rates.
The Mortgage Stress Test
Since the FCA's Mortgage Market Review (MMR), lenders must verify you can still afford repayments if interest rates rise substantially — typically stress-tested at 6–8% above the standard variable rate. This means:
- You might be offered less than 4.5× income if your other outgoings are high.
- You must demonstrate affordability at a higher rate, even if today's rate is much lower.
- Two people with identical salaries can receive different offers based on their spending and existing commitments.
What Lenders Assess Beyond Income
- Credit score and history: Missed payments, defaults, or CCJs significantly reduce the amount lenders offer — or disqualify you entirely from some lenders. Check your credit file with Experian, Equifax, and TransUnion before applying.
- Existing debts: Personal loans, car finance, credit card balances, and student loans all reduce your disposable income and therefore your mortgage affordability.
- Monthly outgoings: Regular subscriptions, childcare costs, maintenance payments, and general living expenses are factored in.
- Employment type: Employed applicants (PAYE) are easiest to assess. Self-employed typically need 2–3 years of tax returns. Contract workers may need to show consistent contract history.
- Number of dependants: Children and other financial dependants reduce assessed disposable income.
LTV Ratios and How They Affect Your Rate
Loan-to-Value (LTV) is your mortgage as a percentage of the property value. A lower LTV (larger deposit) means less risk for the lender — and substantially better interest rates for you.
| LTV | Deposit on £300,000 home | Rate tier |
|---|---|---|
| 95% | £15,000 | Highest rates — limited lenders |
| 90% | £30,000 | More lenders, better rates |
| 85% | £45,000 | Wider choice, improved rates |
| 75% | £75,000 | Competitive rates tier |
| 60% | £120,000 | Best rates available |
Costs Beyond the Deposit — Budget for These
- Stamp Duty Land Tax (SDLT): 0–12% of the purchase price depending on price and buyer type. First-time buyers have a nil-rate band up to £425,000. Use the Stamp Duty Calculator to get your exact figure.
- Solicitor / conveyancing fees: Typically £1,000–£2,500 including searches and Land Registry fees.
- Mortgage arrangement fee: Usually £999–£2,000. Can often be added to the loan, though you then pay interest on it for the mortgage term.
- Survey: A basic valuation (required by lender) may be free or £300–£500. A HomeBuyer Report (recommended) costs £500–£900. A full structural survey costs £800–£1,500 and is worth it for older properties.
- Buildings insurance: Required from exchange of contracts, not completion. Typically £100–£400/year depending on property and location.
- Removals: Professional removals typically cost £500–£2,000 depending on distance and volume.
- Immediate work: Budget for any repairs, decoration, or appliances needed before or shortly after moving in.
Rule of thumb: Budget at least 3–5% of the property price on top of the deposit for all buying costs combined.
Repayment vs Interest-Only
Most residential mortgages in the UK are repayment mortgages: each monthly payment covers both interest and a portion of the capital, so the loan reduces to zero by the end of the term. Interest-only mortgages have lower monthly payments but you only pay interest — the original loan balance remains at the end of the term and must be repaid in full. Interest-only is mainly available for buy-to-let and requires evidence of a repayment strategy.
Types of Mortgage Rate
- Fixed rate: Your rate and monthly payments stay the same for a set period (2, 3, or 5 years are most common). Protects against rate rises. Usually has Early Repayment Charges (ERCs) if you exit early.
- Tracker: Follows the Bank of England base rate plus a set margin. Payments change with base rate moves. Usually no ERCs — good if rates fall or you plan to remortgage soon.
- Standard Variable Rate (SVR): The lender's default rate after a fixed or tracker deal ends. Usually the most expensive option — remortgage before you default onto SVR.
- Discounted: A discount off the SVR for a fixed period. Payments can vary as SVR changes.